1. Field of the Invention
The present invention relates to an image processing apparatus and a control method thereof, and particularly relates to an image processing apparatus that processes an image captured by a digital camera, and a control method for such an image processing apparatus.
2. Description of the Related Art
Viewing images captured using a digital camera on a television receiver (called simply a “TV” hereinafter) has become common in recent years.
Conventional TVs do not have a digital interface, and thus image data has been inputted into the TV from the digital camera and displayed using an analog video input terminal. However, TVs that feature digital interfaces such as HDMI (High-Definition Multimedia Interface) and USB (Universal Serial Bus) are becoming common due to the start of digital broadcasting. In addition to image data, digital interfaces such as these are capable of exchanging control information between the connected devices. Therefore, it is possible for TVs and digital cameras to exchange and display image data in cooperation with each other.
One of the differences between connecting a digital camera to a TV via HDMI and connecting a digital camera to a TV via USB is the location where the image data is decoded. When using an HDMI connection, the image data is decoded in the digital camera and forward transmitted to the TV, whereupon the TV displays the data. On the other hand, when using a USB connection, the digital camera transmits the image data to the TV without decoding it, whereupon the TV decodes the data and displays it.
Considering that TVs are generally operated using a remote control, the USB connection, where the TV decodes the image data, is considered to have a higher level of freedom with regards to manipulation, management, and so on of the image data.
Meanwhile, as browsing images taken with a digital camera on a TV becomes even more commonplace, it is likely that demand will arise for the ability to edit and process images that are being browsed on the TV. For example, it is likely that users will wish to perform red-eye correction, white balance adjustment, and etc. on images displayed on their TVs.
Generally speaking, the JPEG format is an image data format that TVs are capable of decoding; however, as is well-known, the JPEG format is an irreversible-compression encoding format, meaning that the image quality is degraded each time an image is edited or processed after decoding and encoded during storage. However, there are schemes for digital cameras that make it possible to record images without performing irreversible-compression encoding, a representative example of which is recording in the RAW format.
As opposed to the JPEG format, the RAW format does not involve irreversible-compression encoding, and thus the image quality is not degraded even when image data is repeatedly stored. However, TVs normally cannot handle data in the RAW format (called “RAW data” hereinafter). For this reason, it is necessary for the digital camera to convert images from the RAW format to the JPEG format, or record images in the JPEG format in parallel with their RAW format counterparts, and supply those JPEG images to the TV. Therefore, even if RAW data has been present in the digital camera, TVs have nevertheless had to handle the images in the JPEG format (called “JPEG images” hereinafter).
Using, for example, a digital camera connected via a digital interface as a device that performs high-speed processing of RAW format images has been proposed in Japanese Patent Laid-Open No. 2007-6125 (referred to as “Patent Document 1” hereinafter). According to Patent Document 1, a computer in which RAW data is stored outputs the RAW data to a connected digital camera. The digital camera then converts the RAW data into a JPEG image and returns the image to the computer, thereby implementing the process at a higher speed than is possible when using the computer's processor.
However, the method disclosed in Patent Document 1 discusses a computer, which is capable of holding and processing (albeit slowly) RAW data, using a digital camera as a so-called hardware accelerator, and thus the prerequisites differ from TVs, which cannot process RAW data from the outset. Furthermore, Patent Document 1 makes no particular mention of the editing and processing of JPEG images present in the computer.
As illustrated here, the presence or absence of RAW data for a particular image in a digital camera when correcting that image has not been given consideration in conventional image processing apparatuses capable of receiving and correcting images that have undergone irreversible-compression encoding from a digital camera.